/**
 * Copyright (c) 2013-2021 Nikita Koksharov
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.redisson.api.mapreduce;

import java.io.Serializable;
import java.util.Iterator;

/**
 * Reduces values mapped by key into single value.
 * 
 * @author Nikita Koksharov
 *
 * @param <K> key type
 * @param <V> value type
 */
public interface RReducer<K, V> extends Serializable {

    /**
     * Invoked for each key
     * 
     * @param reducedKey - key
     * @param iter - collection of values
     * @return value
     */
    V reduce(K reducedKey, Iterator<V> iter);
    
}
